I use a large channel locks. Although it shouldn't be on there much more than hand-tight.
If you get the Korky 5030bp (Large 3" Flush Valve) kit, it comes with flapper and hardware.
Just out of curiosity, why are you "rebuilding" a fairly-recent toilet? If your fill valve was chattering or making noise, and it was the Korky fill valve, all you need to replace is the little cap in it for $4. (If it wasn't the Korky, that's a good one to get for your Toto, the 528MaxPerformance -- the one with the adjustable refill percentage and the silver-colored cap.) If you were having issues with water leaking past the flapper, just buying a new flapper usually does the trick -- yours would use either the Blue Korky Fits Toto flapper or the Red Korky Fits Toto flapper, depending upon the model of Vespin. Only rarely would you need to replace the flush valve, but I guess you do now.
But if you need a new flush valve, then that Korky one will fit your Toto perfectly, and the twist-lock adjustment on the overflow riser means you don't have to hacksaw it to the right height.
http://www.korky.com/index.php?p=Product&i=1161#.U_Uk_vldVXo
It isn't distributed in a lot of stores, but the big auction site seems to have a few at around $20. The fill valve you can get at both Lowe's and HD:
http://www.homedepot.com/p/Korky-QuietFill-MaxPERFORMANCE-Fill-Valve-528MCM/203145423